What Movie - Bizarre Late 60s / 70s film (or TV) Scene: "Appear / Disappear"

In English but possibly one of those Italian dubbed to English films, had European vibe but could be wrong about that. Also possibly made for TV as I did see it on TV. All I can remember is one scene: Two men on a sidewalk, seems to be wide and clean giving me that European feel as opposed to an cramped NYC style sidewalk, having an existential fight using the power of their minds. One man kept saying "Disappear" and the other saying "Appear" trying to remain in existence. In the end, the weaker one just started desperately saying "Appear, Appear, Appear, Appear," as he knew he was losing the battle. The other just gave one last final "Disappear" and his rival vanished.

I know it's tough in 2022 to ask about a minor Film/TV from the 60s/70s but it was such a bizarre scene, it has stuck with me all these years and I'm dying to know what it was from.